Field
This disclosure relates generally to semiconductor devices, and more specifically, to methods for forming semiconductor devices with stepped bond pads.
Related Art
Electronic component packages can include one or more electronic components such as semiconductor processors. Electrically conductive contact with the electronic components can be established with wire bonds formed on bond pads that are connected to circuitry in the electronic components. The assembly of the electronic components with wire bonds is then encapsulated in a protective covering to seal the electronic components from contaminants and protect the wire bonds from breakage.
As the price of gold rises, it becomes more economical to use less costly conductive materials such as copper, aluminum and silver to replace the use of gold in electronic component packages. For example, gold can be replaced with copper and copper alloys for wire bonds while aluminum can be used as bond pads. As the use of copper wire on aluminum pad becomes more common, various performance issues with these materials arise.
In some cases, in order to meet customer requirements and qualify for shipment, electronic component packages are subject to various tests to simulate performance of the packages over time in expected operating environments. One such test involves subjecting the electronic component packages to temperature extremes such as between −50 to 150 degrees Celsius for a specified duration (for example, 30 minutes per cycle) and a specified number of cycles (for example, 2000 cycles). As the size of the electronic components is continually decreasing and the number of the electronic components in a package is ever-increasing, reliability issues can arise that previously were not an issue with larger wire sizes, larger ball bond sizes and fewer components. For example, as wire size and ball bond size for the wire bonds get smaller, the temperature cycling can cause cracks between the aluminum bond pad and an intermetallic compound at the interface between the copper wire bond and the aluminum bond pad. The cracks can be severe enough to destroy the connection to the circuitry coupled to the bond pad.